Solenoid valve, in particular for fuel-injection pumps

A solenoid valve for a fuel injection pump comprising:

• a housing defining a valve opening surrounded by a valve seat and coupled in fluid communication with a valve inlet and a valve outlet;
• a valve needle moveable relative to the valve seat into a closed position into contact with the valve seat to close the valve opening and into an open position away from the valve seat to open the valve opening;
• a stop member located adjacent to the valve needle to stop the valve needle upon reaching the open position;
• an electromagnet including a winding for driving the valve needle into the closed position upon electrical excitation of the winding;
• a spring member coupled to the valve needle for driving the valve needle into the open position;
• a cable including a supply line coupled to one terminal of the winding and a feedback line coupled to another terminal of the winding for directing current through the winding;
• a piezoelectric member coupled to the stop member for contacting the valve needle upon reaching the open position and generating a signal indicative thereof, wherein the output of the piezoelectric member conducting the higher potential is coupled between the winding and the feedback line and the other output of the piezoelectric member is coupled either between the supply line and winding or to ground or zero potential;
• and
• a control unit including a first output coupled between the supply line and a voltage source for directing current from the voltage source to the winding, and a second output coupled between the feedback line and ground or zero potential by means of a switch element, wherein the open-position signal of the piezoelectric member is transmitted by the feedback line to the second output for tapping the signal.